As a suspension device of this type, there is known such a suspension device as is disclosed in Japanese Patent Laid-Open Publication No. 2007-292255. This conventional suspension device is composed of an actuator, the actuator having a screw shaft threadably engaged with a ball screw nut rotatably and a motor connected to one end of the screw shaft and fixed to a vehicle body, and a hydraulic damper interposed between an axle and the ball screw nut in the actuator to suppress the transfer of a high-frequency vibration to the vehicle body. A relative movement between the vehicle body and the axle is controlled actively with thrust of the actuator.